6L80 Woes

JSJJ388

JSJJ388

GREEN GREMLIN
Joined
Aug 31, 2016
Location
HAMPTONVILLE, NORTH CAROLINA
So we bought an 07 Yukon and all seemed fine. No clunks or anything. But after getting it home, it started kicking down with the least bit of throttle, and then it threw several codes and went into limp mode.

P2714
P0030
P0053
P0070
P0171

Any thoughts? Any recommendations on a good shop around yadkinville? This is above my pay grade.
 
LBarr2002 said:
Ah, ok. That sucks. I was thinking 4l and at least that would have been a relatively "cheap" rebuild. My guy doesn't mess with the 6 speeds, he just replaces instead of rebuilding.
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My guy (does my inspections, but I haven't needed any major work) gave me a quote to flush it, but I dont want to waste the money if it needs more.
 
Infamous1 said:
That 171 is a lean code. Engine issues could def cause trans to act silly. I would address those first.
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Threw a 02 senor code as well. I have that to replace.
 
Well it came out of limp mode. Replaced the 02 sensor. And it definitely drives better. Guess we will see how it goes. Going to do the trans flush either way.
 
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BigBody79 said:
Do you mean flush or drop the pan and replace filter?

I’m not sure I’d do a whole flush. But dropping the pan doing a filter and 6-7 quarts would probably be better.

Full flushes seem to take out transmissions.
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Well, I meant full flush. But I'll definitely consult the mechanic. Fluid is a little too dark imo, but im no expert.
 
NickMaul said:
Most GM six speed users will tell ya drop the pan, replace the filter, and top off with new fluid.
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This.
Fresh fluid will get the contaminated fluid out and the fresh detergents will break up some sludge and typically in small enough particles to let it flow to and be trapped by the filter.

A full flush adds some pressure to the process and tends to break up large chunks of sludge which lodge in other places and starve and destroy transmissions.

Before you ask your flush guy what he recommends ask if he also rebuilds transmissions . If he doesn’t he may not know how many it takes out - if he does he may be drumming up business.

There is zero chance I’d flush that trans. If you wanna feel super helpful do a filter change and re fill and repeat again in 60-90 days.
 
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Thanks for the input folks. This is why I asked.
 
Dodge dealership “serviced” my 68RFE once. I sold the truck shortly after. Transmission detonated about a month later on the guy I sold it to. I wouldn’t flush one unless it’s on its way out and it’s a last resort or a short term bandaid while you’re working out your next move. Granted, it was a dodge transmission and it was doomed from the factory.
 
Well, it seems to be doing a lot better. Still kicks down way easy, but that could just be how these are.
 
Usually the weakest link is the stock torque converter clutch.
 
Ron said:
This.
Fresh fluid will get the contaminated fluid out and the fresh detergents will break up some sludge and typically in small enough particles to let it flow to and be trapped by the filter.

A full flush adds some pressure to the process and tends to break up large chunks of sludge which lodge in other places and starve and destroy transmissions.

Before you ask your flush guy what he recommends ask if he also rebuilds transmissions . If he doesn’t he may not know how many it takes out - if he does he may be drumming up business.

There is zero chance I’d flush that trans. If you wanna feel super helpful do a filter change and re fill and repeat again in 60-90 days.
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Repeat filter changes and draining are what a lot of people recommend. Toyota mechanic recommended a “spill and fill” with filter change 3 -4 times at least 1,000 miles apart and the fluid should be close to all fresh
 
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Mine does kick down very easy and seems to hunt sometimes. Mine is an 11 and I lost the whole trans at 145,000 due to the torque converter dying. I added a drain plug and an external filter. I drain and fill once a year now about 12-15,000 miles.
 
BigBody79 said:
Mine does kick down very easy and seems to hunt sometimes. Mine is an 11 and I lost the whole trans at 145,000 due to the torque converter dying. I added a drain plug and an external filter. I drain and fill once a year now about 12-15,000 miles.
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Curious about adding a drain and external filter? Just for ease of service?
 
That’s the gist of it. My truck needs the exhaust removed/loosened to take off pan. (I’m sure yours does too) Keep in mind I had an extra pan to mess with at the time. I welded a castle nut to the bottom of the pan and got a plug from the parts store. The filter is placed on the inside of the frame rail with the lines going to the cooler.
 
R Q said:
So Joel, what trans have you been used to in the past? I know you're a thrifty guy so maybe this 6 speed is just something you're not used to? They will search for a gear...😉
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5 speed manuals, and th350s. Only other auto that I've had is my ZJ. Wife has always just had small cars. It's definitely just something I'm not used to. Last time my 5 speed started searching for a gear, I had a real bad day lol.
 
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If it had a transmission fluid thermostat I would bypass that so fluid flows to the cooler all the time. To keep the temp down
 
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